Fuse having a fuse head retainer mounted in a closure sleeve



Nov. 22, 1966 D. o. MISARE 3,287,527

FUSE HAVING A FUSE HEAD RETAINER MOUNTED IN A CLOSURE SLEEVE Filed Jan. 6, 1965 INVENTOR. DONALD O. MISARE ATT'YS United States Patent 3,287,527 FUSE HAVING A FUSE HEAD RETAINER MOUNTED IN A CLOSURE SLEEVE Donald 0. Misare, Riverside, Ill., assignor to Joslyn Mfg. and Supply Co., Chicago, Ill., a corporation of Illinois Filed Jan. 6, 1965, Ser. No. 423,762 4 Claims. (Cl. 200-127) The present invention relates generally to an improved fuse construction and more specifically to a new and improved fuse retainer or cap particularly adapted for dropout type fuse cutouts for use on high voltage electrical transmission lines.

Dropout type fuse circuits are known which are adapted to interrupt both low amperage and high amperage faults equally well, with conventional distribution fuse links. One known type of fuse construction provides a fuse cartridge structure for an open type fuse cutout. The cartridge includes an open or vent control arranged to provide single venting of the fuse cartridge on low current faults and to provide double venting on faults up to the maximum interrupting capacity of the cutout. In such presently commercially available structures the double venting is obtained by the provision of an expendible, rupturable cap secured to the closed end of the fuse cartridge so that at a predetermined interrupting current, the cap will rupture to vent the cartridge out at both ends.

In operation, if a light overload condition occurs, the usual explosive action takes place with a consequent dropout motion of the fuse tube. The upper end of the fuse tube is completely closed. This allows sufficient pressure to be built up in the tube to clear faults of a small magnitude. When the fuse blows from a severe short circuit, the violent explosion which otherwise would burst the cartridge is automatically relieved by the vent opening in the top of the cartridge by the rupturing of the frangible section of the expandible cap. This provides double venting of the cartridge from both the top as well as the bottom of the tube. This double venting provides compensating reaction which causes a minimum of stress on the cutout up to its maximum interrupting capacity. On such frangible fuse cap is disclosed and claimed in my copending application Serial Number 392,119

filed August 26, 1964.

Although such frangible fuse caps operate satisfactorily from an electrical point of view, nevertheless some difiiculty has been encountered in that the rupturing cap may propel metal fragments at high velocity. Accordingly such frangible fuse caps are unsatisfactory for use in certain areas such as in residential areas where injury or damage may result from the flying fragments.

Accordingly one object of the present invention is to provide a new and improved fuse construction which overcomes the above mentioned difliculty.

Another object of the present invention is to provide a new and improved fuse construction.

Yet another object of the present invention is to provide a new and improved fuse construction which provides for double venting of the fuse tube upon abnormally high amperage faults without danger from flying metal fragments.

Yet another object of the present invention is to provide a new and improved fuse cap which overcomes the above mentioned difficulties.

Yet another object of the present invention is to provide a new and improved fuse cap which provides for double venting of the fuse tube under high amperage faults without danger of flying fragments.

Further objects and advantages of the present invention will become apparent as the following description pro- "ice ceeds and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of .the specification.

In accordance with these and many other objects of the present invention, there is provided an improved fuse cap or retainer for a fuse structure. The fuse cap is adapted for use with a fuse structure formed of a fuse tube or cartridge, open at the bottom and closed at the top. A fuse link capable of interruption upon abnormal amperage fault extends through the fuse tube. The fuse link as commercially available is provided with a disc shaped head at one end of the fuse tube. The improved fuse cap includes an internally threaded sleeve with a pin extending through the sleeve near one end thereof. The sleeve is threaded on the terminal structure and the pin bears on the head of the fuse so that the head is retained from flying outwardly upon explosive interruption of the fuse link in response to abnormally high current faults.

In operation an abnormally high cur-rent fault is effective to rupture the fuse links and to blow the head of the fuse link upwardly to wrap it around the pin in the fuse cap. The pin will retain the head of the fuse and prevent its being propelled from the fuse tube.

Advantageously the fuse cap or retainer according to the present invention can be. readily and economically manufactured and sold at a minimum cost to provide a highly competitive product. Since the fuse link head will be propelled upwardly at the designated pressure, the operation of the fuse retainer is reliable and affords maximum protection to the fuse cutout. Moreover the pin in the retainer member prevents flying metal fragments from being propelled from the fuse.

For a better understanding of the present invention, reference may be had to the accompanying drawings wherein:

FIGURE 1 is an elevational view of a fuse assembly employing an improved retainer member or fuse cap according to the present invention;

FIGURE 2 is a fragmentary cross sectional elevational view of the fuse tube and cap assembly according to FIGURE 1 and taken \along line 22 of FIGURE 1, shown with its cover removed;

FIGURE 3 is a cross sectional elevational view of the fuse tube and cap assembly of FIGURE 1, substantially like FIGURE 2, but shown after the fuse has ruptured under an abnormally high amperage fault;

FIGURE 4 is an isometric view, partly broken away, illustrating the improved fuse cap or retainer according to the present invention; and

FIGURE 5 is an isometric view of the cap or retainer member of the present invention shown after breakage of the fuse link under an abnormally high current fault.

Referring now to the drawings, and particularly to FIGURE 1 thereof, there is illustrated a fuse assembly 10 according to the present invention. The fuse assembly 10 may be of a type known in the art and more specifically may be similar to the fuse assembly more fully described in the United States Patent 2,862,082 and assigned to the same assignee as the present invention. Briefly, the fuse assembly 10 includes an elongated insulator 12 supported by a suitable bracket 13 from a transmission line superstructure 14 which, in the instant case, is a crossarm of a high voltage current. Upper and lower stationary terminal members 15 and 16 are carried at opposite ends of the insulator 12 for connection to the high voltage transmission line. The lower terminal member 16 is provided with a pair of trunnion supports in the form of book members 18 which are spaced apart and provided with overhanging portions 19. The upper terminal member 16 is also provided with a suitable trunnion portion 20. The upper and lower terminal members and 16 are provided with suitable means for connection to a high voltage transmission line.

A dropout fuse structure, generally illustrated at 25, includes a fuse tube or cartridge 26. A downwardly and rearwardly extending arm 27 extends from the lower end of the fuse tube 26 and is provided with a cross trunnion 28 hooked into the hook members 18 to pivotally interconnect the fuse tube to the lower terminal member 16. The fuse structure 25 further includes an upper terminal 30 adapted to hook or engage with the trunnion portion of the upper terminal member 15 to provide electrical contact with the fuse tube 26.

The fuse assembly 10 is provided with a fuse link 32 having a reduced fusible section 33 adjacent its upper end to provide for rupturing thereof in response to a fault in the power transmission circuit. Additionally the upper end of the fuse link 32 is secured to a disc shaped head 34 resting on the terminal 30. A washer 35 of brass or other electrically conductive material may be interposed between the head 34 and the terminal 30. The lower end of the fuse link 32 extends through the open lower end of the fuse tube 26 and is secured to suitable spring structure 37 adapted to snap the fuse link 32 out of the tube 26 upon rupture of the fuse link 32.

In order to secure the upper end of the fuse link 32, the terminal 30 is provided with an upward threaded portion 38 having suitable external threads to receive a fuse retainer or closure cap 40 according to the present invention. As best illustrated in FIGURES 4 and 5, the fuse retainer 40 is formed of an internally threaded sleeve 41 knurled on the outside. A solid round pin of steel or other suitable material passes through the sleeve 41 near one end thereof and bears against the head 34 of the fuse link as best illustrated in FIGURE 2. The pin will finmly secure the head 34 of the fuse link against the terminal 30 so as to provide for good electrical connection therebetween.

A thin, snug fitting plastic cap 45 covers the open end of the cap 40.

From the above described and illustrated specification,

the operation of the improved fuse retainer is believed clear. However, briefly, it will be understood that in the event of a light overload the fuse cap 34 and washer 35 close the top of the fuse tube 26 so that the fuse tube functions as a single vented tube. The light overload will result in the usual explosive action which takes place within the tube 26 with a consequent dropout motion of the fuse tube. The upper end of the fuse tube 26 is completely closed by the fuse head 34 and washer 35. Sufiicient pressure therefore will build up within the tube 26 to clear the faults of small magnitudes when the tube is functioning as a single vented tube.

When the operations occur from a serious short circuit,

a violent explosion can occur which would otherwise burst the tube 26. However the tube 26 is automatically relieved by failure of the head 34 and washer 35 of the fuse link and tube assembly. This vents the tube 26 from both its upper and lower ends and immediately changes the tube characteristics from a single vented device to a dual vented tube.

Most importantly, according to the present invention, the fuse link head 34 will become very hot and will fuse itself against the pin 42 in the fuse retainer 41 as best illustrated in FIGURES 3 and 4. Consequently no flying metal fragments will be impelled through the top of the fuse tube.

Although the present invention has been described by reference to only a single embodiment thereof, it will be apparent that numerous other modifications and embodiments may be devised by those skilled in the art and it is intended by the appended claims to cover all modifications and embodiments which will fall within the true spirit and scope of the present invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A fuse construction comprising a fuse tube hav ing a terminal structure at one end; a fuse link capable of interruptions upon abnormal amperage faults and eX- tending through the fuse tube and provided with a disc shaped head at one end of said tube; and a retainer threadingly engaging the terminal structure to retain said head to provide electrical connection thereto; said retainer including an internally-threaded sleeve and a pin secured transversely through said sleeve near one end thereof with said sleeve threaded on said terminal structure and said pin bearing on said head whereby said head is retained from flying outward upon explosive interruption of said fuse link in response to high current faults.

2. A fuse construction comprising a fuse tube having a terminal structure at one end; a fuse link capable of interruptions upon abnormal amperage faults and extending'through the fuse tube and provided with a head seated against one end of said tube; and a retainer including an internally threaded sleeve and a pin secured transversely through said sleeve near one end thereof with said sleeve threaded on said terminal structure and said pin bearing on said head whereby said head is retained from flying outward upon explosive interruption of said fuse link in response to high current faults.

3. A fuse construction comprising a fuse tube having a terminal structure at one end; a fuse link capable of interruptions upon abnormal amperage faults and extending through the fuse tube and provided with a head seated against one end of said tube; and a retainer including a sleeve secured to said terminal structure, and a pin secured transversely through said sleeve, said pin bearing on said head.

4. A fuse structure as set forth in claim 3 above wherein said pin is a solid steel rod.

References Cited by the Examiner UNITED STATES PATENTS 1,967,543 7/ 1934 Smythe 2001 17 1,970,634 8/ 1934 Steinmayer 2001l7 2,183,751 12/1939 McMahon et al. 200l17 2,353,528 7/1944 Triplett 200114 X BERNARD A. GILHEANY, Primary Examiner. 

1. A FUSE CONSTRUCTION COMPRISING A FUSE TUBE HAVING A TERMINAL STRUCTURE AT ONE END; A FUSE LINK CAPABLE OF INTERRUPTIONS UPON ABNORMAL AMPERAGE FAULTS AND EXTENDING THROUGH THE FUSE TUBE AND PROVIDED WITH A DISC SHAPED HEAD AT ONE END OF SAID TUBE; AND A RETAINER THREADINGLY ENGAGING THE TERMINAL STRUCTURE TO RETAIN SAID HEAD TO PROVIDE ELECTRICAL CONNECTION THERETO; SAID RETAINER INCLUDING AN INTERNALLY THREADED SLEEVE AND A PIN 